Nuclear magnetic resonance (NMR) spectroscopy using natural abundance and/or isotopically enriched nuclear centers will be applied in the investigation of the chemistry and reaction kinetics of the following metastable metabolites of the anticancer drug cyclophosphamide: cis- and trans-4-hydroxycyclophosphamide, aldophosphamide, 3,4,-dehydrocyclophosphamide, and phosphoramide mustard. Synthetic samples of 3-hydroxycyclophosphamide will be evaluated with regard to its possible role in cyclophosphamide metabolism, and various phosphoramide mustards will be synthesized and studied by NMR to gauge structure-reactivity effects.